The field of peristalic pumps is, on the one hand, fairly well developed. However, the peristalic pumps known to the Applicant have various shortcomings. Examples of prior art peristalic pumps include those shown in U.S. Pat. Nos. 3,358,609; 4,138,205; 4,179,249; 4,231,725; and 4,552,516. For example patents '249, '725 and '516 show peristalic pumps which employ a rotor having a plurality of compression surfaces operative to cause peristalic action on a compressible flow tube; these patents further have a means for loading or adjustment of a compressible flow tube relative to the pump rotor. These prior art pumps use reaction surfaces on moveable reaction members, termed "clam shells", which are moved between an open position which permits loading and removal of a compression tube, and a closed position where the tube is held in a predetermined position to facilitate peristalic pumping; a disadvantage of these prior art pumps is that a significant amount of time is required to first stop the pump and then operate the clam shells so as to change or adjust the compression tube.